I want to bind two controls like font size slider and text box, and each control is on different window on wpf, so how can I bind them?
Here's an example of how to do it:
1) Create a WPF project.
2) Change the contents of the MainWindow.xaml to the following (don't forget to correct the namespaces in all the code that I'm posting, for example in my code the namespace is WpfApplication2):
<Window x:Class="WpfApplication2.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<StackPanel>
<Button Content="Settings Window" Click="SettingsWindowButton_OnClick"/>
<Button Content="Bound Window" Click="BoundWindowButton_OnClick"/>
</StackPanel>
</Window>
3) Change the contents of the MainWindow.xaml.cs to the following:
namespace WpfApplication2
{
using System.Windows;
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
ViewModel viewModel = new ViewModel();
public MainWindow()
{
InitializeComponent();
}
private void SettingsWindowButton_OnClick(object sender, RoutedEventArgs e)
{
var settingsWindow = new SettingsWindow();
settingsWindow.DataContext = viewModel;
settingsWindow.Show();
}
private void BoundWindowButton_OnClick(object sender, RoutedEventArgs e)
{
var boundWindow = new BoundWindow();
boundWindow.DataContext = viewModel;
boundWindow.Show();
}
}
}
4) Create a class named ViewModel in your project with the following code:
namespace WpfApplication2
{
using System.ComponentModel;
public class ViewModel : INotifyPropertyChanged
{
private int _fontSizeSetting = 10;
public event PropertyChangedEventHandler PropertyChanged;
public int FontSizeSetting
{
get { return _fontSizeSetting; }
set
{
_fontSizeSetting = value;
OnPropertyChanged("FontSizeSetting");
}
}
protected virtual void OnPropertyChanged(string propertyName)
{
var handler = PropertyChanged;
if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
}
}
}
5) Add two new Windows to your project named BoundWindow and SettingsWindow with the following markup:
<Window x:Class="WpfApplication2.BoundWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="BoundWindow" Height="300" Width="300">
<Grid>
<TextBox FontSize="{Binding FontSizeSetting, Mode=TwoWay}" Text="test..."/>
</Grid>
</Window>
-
<Window x:Class="WpfApplication2.SettingsWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="SettingsWindow" Height="300" Width="300">
<Grid>
<Slider Value="{Binding FontSizeSetting, Mode=TwoWay}" Minimum="10" Maximum="100"/>
</Grid>
</Window>
Now everything should be working as expected. What you basically did was to create a view model to set as the DataContext of your Windows. They both bind to the FontSizeSetting property of your view model, and when you change it in one window, WPF binding system takes care of changing the other value automatically.
Related
I have two xaml toggles in separate files that I want to update simultaneously (if one is switched on the other should be too (and vice versa). My first switch in xaml is:
<Switch Grid.Column="1" x:Name="toggleSwitch1" IsToggled="true" Toggled="OnToggled"/>
Using C# how can I return a boolean value of this switch so that I can update another switch simultaneously? Then once retrieving the value, how can I update the xaml of the toggle status for the other switch?
Your Switch control means, as I can understand, that you using UWP, but I'm not sure.
Anyway, the idea is to bind both controls IsToggled properties to same property of some ViewModel:
using System.ComponentModel;
using System.Runtime.CompilerServices;
namespace MyWPFApp
{
public class ControlsViewModel : INotifyPropertyChanged
{
private bool switchToggled;
public bool SwitchToggled
{
get => switchToggled;
set
{
switchToggled = value;
OnPropertyChanged(nameof(SwitchToggled));
}
}
public ControlsViewModel() { }
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged([CallerMemberName]string propertyName = "") =>
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
Then in XAML of both Windows set bindings to Switch control (in my example - CheckBox control):
<!-- Window 1 -->
<Window x:Class="MyWPFApp.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:MyWPFApp"
mc:Ignorable="d"
Title="Window 1" Height="100" Width="300">
<Grid>
<CheckBox Content="Window1 CheckBox"
IsChecked="{Binding SwitchToggled}"/>
<!-- Replace IsChecked to IsToggled property -->
</Grid>
</Window>
<!-- Window 2 -->
<Window x:Class="MyWPFApp.Window2"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:MyWPFApp"
mc:Ignorable="d"
Title="Window 2" Height="100" Width="300">
<Grid>
<CheckBox Content="Window2 CheckBox"
IsChecked="{Binding SwitchToggled}"/>
<!-- Replace IsChecked to IsToggled property -->
</Grid>
</Window>
Code-behind of both Windows in example is same:
using System.Windows;
namespace MyWPFApp
{
public partial class Window1 : Window // or public partial class Window2
{
public Window1(ControlsViewModel cvm) // or public Window2
{
InitializeComponent();
DataContext = cvm;
}
}
}
And when calling that example Windows to show from Main one, you creating ControlsViewModel instance and pass it to both:
using System.Windows;
namespace MyWPFApp
{
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
var cvm = new ControlsViewModel();
new Window1(cvm).Show();
new Window2(cvm).Show();
}
}
}
So checking/unchecking (toggle/untoggle) one of them will affect another and vice versa. Also, you can change SwitchToggled from code somewhere, which would affect both controls too.
Please note, that this is just example to try explain the idea. More MVVM pattern explanations and examples you can find at MSDN.
I'm new to WPF so bear with me. I have a WinForms Application that I am trying to redo in WPF. In my current WinForms Application, I stick all my Controls into one Form, and hide/show them based on what buttons are hit, as well as making use of a second form.
My goal: Create different views to switch between smoothly based on what button is hit, instead of hiding Controls or making separate Forms and then hiding those.
I currently have a MainWindow view (My initial launch window), where with a button, I switch to my CreateAccount view. What I am having issues with is, how can I make my button in my CreateAccount go "back" to my MainWindow?
My end goal is to be able to switch between 4 views based off Button clicks.
Here is my MainWindow.xaml
<Window x:Class="MusicPlayer.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:MusicPlayer"
xmlns:Views="clr-namespace:MusicPlayer.Views"
xmlns:ViewModels="clr-namespace:MusicPlayer.ViewModels"
Title="MainWindow" Height="450" Width="800">
<Window.Resources>
<DataTemplate x:Name="CreateAccountTemplate" DataType="{x:Type ViewModels:CreateAccountViewModel}">
<Views:CreateAccountView DataContext="{Binding}"/>
</DataTemplate>
</Window.Resources>
<Grid>
<Button x:Name="TestButton" Content="Button" HorizontalAlignment="Left" Margin="164,182,0,0" VerticalAlignment="Top" Height="61" Width="68" Click="CreateAccountView_Clicked"/>
<PasswordBox HorizontalAlignment="Left" Margin="164,284,0,0" VerticalAlignment="Top" Width="120"/>
<ContentPresenter Content="{Binding}"/>
</Grid>
</Window>
My MainWindow.xaml.cs
using System;
using System.Windows;
using MusicPlayer.ViewModels;
namespace MusicPlayer {
public partial class MainWindow : Window {
public MainWindow() {
InitializeComponent();
}
protected override void OnClosed(EventArgs e) {
base.OnClosed(e);
Application.Current.Shutdown();
} //end of onClosed
private void CreateAccountView_Clicked(object sender, RoutedEventArgs e) {
DataContext = new CreateAccountViewModel();
} //end of CreateAccountView_Clicked
}
}
And here is my CreateAccount.xaml
<UserControl x:Class="MusicPlayer.Views.CreateAccountView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:Views="clr-namespace:MusicPlayer.Views"
xmlns:ViewModels="clr-namespace:MusicPlayer.ViewModels"
mc:Ignorable="d"
d:DesignHeight="450" d:DesignWidth="800">
<UserControl.Resources>
</UserControl.Resources>
<Grid Background="White">
<Button Content="Button" HorizontalAlignment="Left" Margin="276,279,0,0" VerticalAlignment="Top" Height="60" Width="59" Click="Button_Click"/>
</Grid>
</UserControl>
And my CreateAccountView.xaml.cs
using System.Windows;
using System.Windows.Controls;
using MusicPlayer.ViewModels;
namespace MusicPlayer.Views {
public partial class CreateAccountView : UserControl {
//public static readonly DependencyProperty TestMeDependency = DependencyProperty.Register("MyProperty", typeof(string), typeof(CreateAccountView));
public CreateAccountView() {
InitializeComponent();
}
private void Button_Click(object sender, RoutedEventArgs e) {
DataContext = new MainWindowViewModel();
}
}
}
It seems to me that your current attempt is on the right track. The main issue with the code you posted is that the CreateAccountView.Button_Click() handler doesn't have access to the DataContext property it should be setting:
private void Button_Click(object sender, RoutedEventArgs e) {
DataContext = new MainWindowViewModel();
}
This DataContext property belongs to the CreateAccountView user control. However, this is not the controlling context for what's being displayed. So changing the value of that DataContext property doesn't have any useful effect. (Indeed, a user control should not set its own DataContext property at all, because doing so discards whatever context the client code using that user control had set.)
There's not enough context to know exactly what the best way for you to do this would be. I don't think it would be possible to provide enough context here on Stack Overflow. The overall architecture will depend on too many little details about your program. But, one way to approach this which I think is a good one would be this:
Create a "main" view model that governs the overall behavior of the app
Create individual view models that relate to different states of the UI
Have the main view model configure the individual view models to switch the current view model as appropriate, given the user input (e.g. clicking buttons)
Translating that into code, looks something like this…
First, the view models:
class MainViewModel : NotifyPropertyChangedBase
{
private object _currentViewModel;
public object CurrentViewModel
{
get => _currentViewModel;
set => _UpdateField(ref _currentViewModel, value);
}
private readonly HomeViewModel _homeViewModel;
private readonly Sub1ViewModel _sub1ViewModel;
private readonly Sub2ViewModel _sub2ViewModel;
public MainViewModel()
{
_sub1ViewModel = new Sub1ViewModel
{
BackCommand = new DelegateCommand(() => CurrentViewModel = _homeViewModel)
};
_sub2ViewModel = new Sub2ViewModel
{
BackCommand = new DelegateCommand(() => CurrentViewModel = _homeViewModel)
};
_homeViewModel = new HomeViewModel
{
ShowSub1Command = new DelegateCommand(() => CurrentViewModel = _sub1ViewModel),
ShowSub2Command = new DelegateCommand(() => CurrentViewModel = _sub2ViewModel)
};
CurrentViewModel = _homeViewModel;
}
}
class HomeViewModel : NotifyPropertyChangedBase
{
private ICommand _showSub1Command;
public ICommand ShowSub1Command
{
get => _showSub1Command;
set => _UpdateField(ref _showSub1Command, value);
}
private ICommand _showSub2Command;
public ICommand ShowSub2Command
{
get => _showSub2Command;
set => _UpdateField(ref _showSub2Command, value);
}
}
class Sub1ViewModel : NotifyPropertyChangedBase
{
private ICommand _backCommand;
public ICommand BackCommand
{
get => _backCommand;
set => _UpdateField(ref _backCommand, value);
}
}
class Sub2ViewModel : NotifyPropertyChangedBase
{
private ICommand _backCommand;
public ICommand BackCommand
{
get => _backCommand;
set => _UpdateField(ref _backCommand, value);
}
}
Of course, these view models contain only the implementation details needed to handle the UI switching. In your program, each would also include the stuff specific to each view state that you need.
In my little sample, the "home" view contains a couple of buttons, used to select the individual sub-views available:
<UserControl x:Class="WpfApp1.HomeView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="450" d:DesignWidth="800">
<StackPanel Orientation="Horizontal">
<TextBlock Text="Home: "/>
<Button Content="Sub1" Command="{Binding ShowSub1Command}"/>
<Button Content="Sub2" Command="{Binding ShowSub2Command}"/>
</StackPanel>
</UserControl>
The sub views just contain the button required to go back to the home view:
<UserControl x:Class="WpfApp1.Sub1View"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="450" d:DesignWidth="800">
<StackPanel Orientation="Horizontal">
<TextBlock Text="Sub1 View: "/>
<Button Content="Back" Command="{Binding BackCommand}"/>
</StackPanel>
</UserControl>
<UserControl x:Class="WpfApp1.Sub2View"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="450" d:DesignWidth="800">
<StackPanel Orientation="Horizontal">
<TextBlock Text="Sub2 View: "/>
<Button Content="Back" Command="{Binding BackCommand}"/>
</StackPanel>
</UserControl>
Finally, the main window sets the main view model, and declares templates to use for each of the specific sub views:
<Window x:Class="WpfApp1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:l="clr-namespace:WpfApp1"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800">
<Window.DataContext>
<l:MainViewModel/>
</Window.DataContext>
<Window.Resources>
<DataTemplate DataType="{x:Type l:HomeViewModel}">
<l:HomeView/>
</DataTemplate>
<DataTemplate DataType="{x:Type l:Sub1ViewModel}">
<l:Sub1View/>
</DataTemplate>
<DataTemplate DataType="{x:Type l:Sub2ViewModel}">
<l:Sub2View/>
</DataTemplate>
</Window.Resources>
<StackPanel>
<ContentControl Content="{Binding CurrentViewModel}"/>
</StackPanel>
</Window>
Importantly, you'll see that none of the view objects include any code-behind. It's not necessary when you approach the problem this way, at least not for the purpose of controlling basic behaviors in the code. (You may still wind up with code-behind for view objects, but this will usually only be for the purpose of implementing specific user-interface behaviors unique to that view object, not for dealing with the view model state.)
Using this approach, you let WPF do as much of the heavy-lifting as possible. It also decouples all of the view model objects from each other. There's a clear hierarchy: only the top-level "main" view model even knows about the other view models. This allows the sub-view models ("home", "sub1", and "sub2") to be reused as necessary in other scenarios without any modification or special-case handling within them.
Here are the helper classes I used above:
class NotifyPropertyChangedBase : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected void _UpdateField<T>(ref T field, T newValue,
Action<T> onChangedCallback = null,
[CallerMemberName] string propertyName = null)
{
if (EqualityComparer<T>.Default.Equals(field, newValue))
{
return;
}
T oldValue = field;
field = newValue;
onChangedCallback?.Invoke(oldValue);
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
class DelegateCommand : ICommand
{
private readonly Action _execute;
public DelegateCommand(Action execute)
{
_execute = execute;
}
#pragma warning disable 67
public event EventHandler CanExecuteChanged;
#pragma warning restore
public bool CanExecute(object parameter) => true;
public void Execute(object parameter) => _execute();
}
I'm sorry if this is a stupid question or doesn't even fall under what I'm asking, but I'm new to WPF and I can't seem to get the hang of it. Right now I'm doing something akin to https://www.c-sharpcorner.com/article/use-inotifypropertychanged-interface-in-wpf-mvvm/ and I've run into a problem. When I try to execute my code:
namespace DPS_Calculator_Prototype
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow() {
InitializeComponent();
}
}
public class NotifyPropertyChanged : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public void RaisePropertyChange(string propertyName) {
PropertyChanged?.Invoke(this, new
PropertyChangedEventArgs(propertyName));
}
}
public class Calculator: NotifyPropertyChanged
{
private string _damage;
public string Damage {
get { return _damage; }
set {
_damage = value;
RaisePropertyChange("Damage");
}
}
}
namespace UseOf_INotifyPropertyChanged
{
public class MainWindowViewModel : Calculator
{
public MainWindowViewModel() {
Damage = "7";
}
}
}
}
I get the error that "The type or namespace name 'ViewModel' does not exist in the namespace 'DPS_Calculator_Prototype.UseOf_INotifyPropertyChanged' (are you missing an assembly reference?)"
and
"The name "MainWindowViewModel" does not exist in the namespace 'clr-namespace:DPS_Calculator_Prototype.UseOf_INotifyPropertyChanged.ViewModel'."
and
"The type 'VM:MainWindowViewModel' was not found. Verify that you are not missing an assembly reference and that all referenced assemblies have been built."
I get the first error twice, once in MainWindow.g.cs and another in MainWindow.xaml. The other two are all in MainWindow.XAML If anyone can tell me what I'm doing wrong then that would be great. Here's the XAML file:
<Window x:Class="DPS_Calculator_Prototype.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:VM="clr-namespace:DPS_Calculator_Prototype.UseOf_INotifyPropertyChanged.ViewModel"
xmlns:local="clr-namespace:DPS_Calculator_Prototype"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800">
<Window.DataContext>
<VM:MainWindowViewModel x:Name="VMMainWindow">
</VM:MainWindowViewModel>
</Window.DataContext>
<Grid>
<TextBox HorizontalAlignment="Left" Height="23" TextWrapping="Wrap"
Text="{Binding Damage}" VerticalAlignment="Top" Width="120"
Margin="78,28,0,0" TextChanged="TextBox_TextChanged"/>
</Grid>
</Window>
That's one of the worst "copy and paste" jobs I've ever seen guy...
I don't know where to start.
Just to run the application you MUST:
change the namespace VM as follows;
xmlns:VM="clr-namespace:DPS_Calculator_Prototype.UseOf_INotifyPropertyChanged"
DPSCalculatorPrototype.ViewModel doesn't exist.
The TextBox_TextChanged doesn't exist inside the codebehind of the window. You must add the method
private void TextBox_TextChanged(object sender, TextChangedEventArgs e)
{
//Do your stuffs
}
in the MainWindow class.
In order to avoid headaches to you or who is reading your code, you
SHOULD
use one .cs file for each class.
Avoid to nest namespaces inside the same .cs file and create a folder tree that replicates the namespace structure. In your snippet just create a UseOf_INotifyPropertyChanged folder inthe root and create the MainWindowViewModel class inside that.
The purpose of a namespace must be clear reading the code. Create a DPS_Calculator_Prototype.ViewModels and put all application viewmodel inside it.
I just tried using different namespaces and keep them more simple. And it works.
DPSCalculatorPrototype.ViewModel
namespace DPSCalculatorPrototype.ViewModel
{
public class MainWindowViewModel : Calculator
{
public MainWindowViewModel()
{
Damage = "7";
}
}
}
DPSCalculatorPrototype
namespace DPSCalculatorPrototype
{
public class Calculator : NotifyPropertyChanged
{
private string _damage;
public string Damage
{
get { return _damage; }
set
{
_damage = value;
RaisePropertyChange("Damage");
}
}
}
public class NotifyPropertyChanged : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public void RaisePropertyChange(string propertyName)
{
PropertyChanged?.Invoke(this, new
PropertyChangedEventArgs(propertyName));
}
}
}
MainWindow.xaml
<Window x:Class="DPSCalculatorPrototype.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:VM="clr-namespace:DPSCalculatorPrototype.ViewModel"
xmlns:local="clr-namespace:DPSCalculatorPrototype"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800">
<Window.DataContext>
<VM:MainWindowViewModel x:Name="VMMainWindow"></VM:MainWindowViewModel>
</Window.DataContext>
<Grid>
<TextBox HorizontalAlignment="Left" Height="23" TextWrapping="Wrap" Text="{Binding Damage}" VerticalAlignment="Top" Width="120" Margin="78,28,0,0" TextChanged="TextBox_TextChanged" />
</Grid>
</Window>
MainWindow.xaml.cs
namespace DPSCalculatorPrototype
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
private void TextBox_TextChanged(object sender, System.Windows.Controls.TextChangedEventArgs e)
{
}
}
}
The reason you are seeing these errors is that WPF is looking in the namespaces mentioned and cannot seem to find what you're looking for. If you take a look at your XAML code you can see the line that says:
xmlns:VM="clr-namespace:DPS_Calculator_Prototype.UseOf_INotifyPropertyChanged.ViewModel"
This is what is declaring to use the namespace, so we need to point it to the correct area. Change your XAML to look like the following:
<Window x:Class="DPS_Calculator_Prototype.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:VM="clr-namespace:DPS_Calculator_Prototype.UseOf_INotifyPropertyChanged"
xmlns:local="clr-namespace:DPS_Calculator_Prototype"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800">
<Window.DataContext>
<VM:MainWindowViewModel x:Name="VMMainWindow">
</VM:MainWindowViewModel>
</Window.DataContext>
<Grid>
<TextBox HorizontalAlignment="Left" Height="23" TextWrapping="Wrap" Text="
{Binding Damage}" VerticalAlignment="Top" Width="120" Margin="78,28,0,0"
TextChanged="TextBox_TextChanged"/>
</Grid>
</Window>
You were getting these errors because you had "ViewModel" in the namespace declaration, and this namespace doesn't exist, and as such, nothing exists in it.
I am trying bind an int to a label in a simple application. The idea is, when a button is pressed, the int, and hence the label, is updated.
I have simplified the code as much as I can but I am not able to see the problem.
I think the issue is with NotifyPropertyChanged(String propertyName) as at runtime start the label's content is updated with the value of the int. However, when the int updates, the label does not.
MainWindow.xaml
<Window x:Class="Press.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800">
<StackPanel>
<StackPanel Orientation="Horizontal">
<Label Content="Presses: "/>
<Label Content="{Binding Path=PressCount}"/>
</StackPanel>
<Button Content="Press Me" Click="PressMe_Click"/>
</StackPanel>
</Window>
MainWindow.xaml.cs
using System;
using System.Windows;
using System.ComponentModel;
using System.Runtime.CompilerServices;
namespace Press
{
public partial class MainWindow : Window
{
public int pressCount = 0;
public int PressCount {
get {
return pressCount;
}
private set {
if(value != pressCount)
{
pressCount = value;
NotifyPropertyChanged();
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public MainWindow()
{
InitializeComponent();
DataContext = this;
}
private void PressMe_Click(object sender, RoutedEventArgs e)
{
PressCount++;
Console.WriteLine(PressCount);
}
}
}
You need MainWindow to implement the interface INotifyPropertyChanged
Could you tell me how to in pure MVVM way call (I mean open/show) child window from parent window. Let's say I have two Views:
MainWindow.cs (MainWindow.xaml) - parent window (DataContext = new MainWindowViewModel())
Window.cs (Window.xaml) - child window (DataContext = new WindowViewModel())
And corresponding ViewModel classes:
MainWindowViewModel.cs
WindowViewModel.cs
I would like my window to be opened after button click (button that is on the MainWindow view). Because of that I have defined command binding in MainWindow.xaml:
<Button x:Name="buttonOpenWindow" Content="Open window..." Width="100" Height="20" Command="{Binding OpenWindowCmd}"/>
And MainWindowViewModel.cs piece:
public ICommand OpenWindowCmd { get; set; }
public MainWindowViewModel()
{
OpenWindowCmd = new RelayCommand(o => OpenWindow());
}
private void OpenWindow()
{
// What to put here?
}
In Window.xaml I added something like that:
<Window x:Class="Namespace.View.Window"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
xmlns:vm="clr-namespace:Namespace.ViewModel"
Title="Title" Height="300" Width="325" Visibility="{Binding IsWindowVisible, Converter={StaticResource BooleanToVisibilityConverter}}">
<Window.Resources>
<BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter"/>
</Window.Resources>
(...)
And the WindowViewModel.cs:
using System.ComponentModel;
using System.Runtime.CompilerServices;
using Namespace.Annotations;
namespace Namespace.ViewModel
{
public class WindowViewModel : INotifyPropertyChanged
{
private bool _isWindowVisible;
public bool IsWindowVisible
{
get { return _isWindowVisible; }
set
{
_isWindowVisible = value;
OnPropertyChanged(nameof(IsWindowVisible));
}
}
public event PropertyChangedEventHandler PropertyChanged;
[NotifyPropertyChangedInvocator]
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
}
I am not sure what to do next and if that approach is correct. I found some services implementations in the forum, but I thought of using just Visibility property instead (but not sure if it is possible). I need to somehow change the IsWindowVisible in one of the view models I suppose. Could anyone suggest how to gently handle such sub window opening?
If I understood well, you need something like this:
private void OpenWindow()
{
WindowViewModel wvm = new WindowViewModel();
Window win = new Window()
{
DataContext = wvm;
};
win.Show();
}
If you don't like this solution then try the one from the comments with IWindowService.
In any case it makes no sense to use a Visibility property.